Without Boldin, who was unloaded to the 49ers in exchange for a sixth-round draft pick following a contract dispute over his $6 million base salary when he refused to accept a pay cut, the 49ers' receiving corps would lack a healthy proven presence.

Judging from reports from the 49ers' organized team activities, Boldin is poised to make an immediate impact with his new football team after contributing heavily to defeating them in the Super Bowl as a member of the Ravens.

Boldin didn't drop a pass Tuesday, according to reports, dominating the secondary as the quarterbacks' most heavily targeted receiver.

“Well, very impressed,” 49ers coach Jim Harbaugh told Bay Area reporters. "You got a good look at what he’s been doing. Really picked up the system fast and making plays. Big catches in tight areas. You saw what we’ve been seeing for a couple of weeks now, very good.”

Boldin is expected to assume a low-key leadership role, much as he did in Baltimore.

“That could be something that develops," Harbaugh said. "Right now, Anquan is not a talkative guy. He’s not a small-talk guy. He’s just very serious about competing, and very serious about football and winning. I think it’ll speak volumes if the young guys observe that.”

Boldin caught 65 passes for 921 yards and four touchdowns last season.